1. Field of the Invention
The present invention relates to a device for decreasing the flow of heat through a barrier--such as a wall, window, door, or ceiling of a building--and into an area adjacent to the barrier and, in particular, to such a device having at least one flexible insulating sheet which, when the device is deployed, forms insulating air spaces and a sealed perimeter.
2. Description of the Prior Art
The high price and limited supply of energy needed to heat and cool buildings have encouraged owners and operators of buildings to seek ways of decreasing the flow of heat from or into their buildings through the barriers thereof--such as their floors, walls, ceilings, and windows.
Since much of the flow of heat into or out of a well insulated building occurs through its windows, workers in the art have developed improved shades and curtains for decreasing the flow of heat through windows. Hopper U.S. Pat. Nos. 4,039,019 and 4,194,550 and Rasmussen U.S. Pat. No. Re. 30,254 disclose, respectively, a shade and a curtain, each having thermal insulating properties. In both cases, the objective is to provide compartmentalized structures to minimize heat transmission by radiation, conduction, and convection. The Hopper patents, for example, employ multiple sheets of flexible material held in spaced-apart relationship by spacer members when the shade is extended. Rasmussen, on the other hand, uses a plurality of flexible tubular members joined along their long dimension and capable of collapsing to permit retraction of the curtain. The major problems associated with such known shades and curtains are the cost of manufacturing them and their bulk when they are in a retracted condition, respectively. Accordingly, a need exists for a shade having multiple sheets and insulating air spaces therebetween that is relatively inexpensive to manufacture and that consumes a minimum of volume when it is in its retracted position.